Heat treating apparatus for hardening selective workpiece regions while protecting adjacent regions against hardening



12, 1969 w. CORTEGGIANO ET AL 3,4

HEAT TREATING APPARATUS FOR HARDENING SELECTIVE WORKIIECE REGIONS WHILE PROTECTING ADJACENT REGIONS AGAINST HARDENING Filed March 2, 1966 Vhikdkm E i m VNUFGDM V w VZAOTPQFM y VNVTSDM w ZOCHPm INVENTORS WITNESSES:

R N E L G O A H MB I wail

United States Patent U.S. Cl. 266-4 4 Claims ABSTRACT OF THE DISCLOSURE Apparatus for hardening at least the cup end of rocker arms while preventing the adjacent bore-containing portions of such arms from becoming hardened. Induction heating means disposed above a coolant bath provides for the' selective heating of the cup end of the rocker arm while its bore-containing portion remains immersed in the bath for protection from such heating; prior to quenching such heated cup end to complete its hardening.

The present invention provides apparatus for performing, and includes the steps of, transporting the workpiece in a vertical attitude such that the tome-hardened end disposed furthermost from the portion to-be-hardness-protected is disposed lowermost and the end immediately adjacent to the portion to-be-hardness-protected is uppermost; transporting such workpiece while in such attitude horizontally into consecutive subjection to a first heating means which raises the lower end of the workpiece up to a hardness-requirement temperature, followed by introduction of such lower heated end of the workpiece to a quenching medium to complete the act of hardening thereof, followed by subjection of the upper end of the workpiece to a second heating means for raising its temperature up to a hardness-requirement temperature while the remainder of the workpiece disposed beneath such end is subjected to a liquid heat-conducting medium, followed by introduction of quenching medium to such upper heated end to complete hardening thereof.

Other objects, features, and advantages of the invention will become apparent from the following detailed description thereof when taken in connection with the accompanying drawing, in which:

The single figure illustrates schematically in a threedimensional view an illustrative embodiment of an apparatus constructed in accord with features of the present invention.

Referring to the drawing, an illustrative apparatus for performing the method of the present invention is shown in conjunction with its use for hardening opposite ends of elongated workpieces in the form of rocker arms, while protecting the bore-containing portion of such arm from becoming hardened. Accordingly, the apparatus comprises a frame construction 7 on which is disposed a conveyor chain arrangement 10 having links 12 on which are pivotally mounted respective workpiece holders 14 for carrying the rocker arm workpieces 16 in a longitudinal direction consecutively through a plurality of stations in which various operations are performed on such workpieces. As the conveyor chain 10 travels through Station 1, an operation will load the rocker arm 16 onto the workpieces holders 14, as by insertion of the bore-containing portion 18 of the rocker arms between spaced-apart holder arms 20 at the upper end of each respective workpiece holder in such an attitude that the cup end 22 of each rocker arm 16 extends vertically 3,460,815 Patented Aug. 12, 1969 above such bore-containing portion and the pad end 24 of such rocker arm projects downwardly. Retention of each rocker arm 16 between the spaced-apart arms 20 of a respective workpiece holder 14 may be obtained by any suitable means such as a ball detent means, not shown.

The conveyor chain 10 moves the workpiece holders 14 next through Station 2, where the lowermost pad ends 24 of the rocker arms 16 are subjected to heating by a first heating means in the form of an elongated induction heating coil 28 suitably constructed and mounted on the frame 7 to permit such pad ends to pass therethrough and become heated to a suitable hardness-requirement temperature.

The pad ends 24 of the rocker arms are located a suflicient distance away from the bore-containing portions 18 of such arms that such bore-containing portion will not experience any significant rise in temperature before the chain 10 transports the rocker arms into Station 3 where a cam 32, extending along the path of travel of the chain, causes tilting of the workpiece holders 14 about their swivel mounts on respective chain links 12, through the medium of a roller follower 34 and an arm 36, and effects submergence of the lower pad end 24 of such rocker arms into a liquid cooling and quenching medium 40 contained in a cooling and quenching tank 42 to complete the step of hardening such pad end of the rocker arms.

Following the above, continued movement of the conveyor chain 10 results in a further rocking movement of the workpiece holders 14 by the cam 32 within Station 4 to the extent that only the uppermost cup ends 22 of the rocker arms 16 lie above the surface of the liquid 40 in the quenching and cooling tank 42 while such uppermost cup ends of the rocker arms are subjected to the heating etfect of a second heating means in the form of a second induction heating coil 46, in an elongated inverted trough-shaped configuration, which heats such cup ends to a suitable hardness-requirement temperature, while the adjacent bore-containing portions 18 of the rocker arms are protected from becoming similarly heated by the presence of such portions within the surrounding liquid 40 in the tank 42.

Following this, continued movement of the conveyor chain It) results in complete submergence of the workpiece 16, including the heated cup ends: 22, by action of the cam 32, and further tilting of the workpiece holders 14, to complete the hardening of such cup ends. This latter quenching of the cup ends 22 occurs during travel of the convey-or chain through Station 5.

Finally, the chain 10 transports the workpiece holders 14 and rocker arm workpieces 16 through Station 6 where the cam 32 causes the workpiece holders 14 to tilt upright and raise the rocker arms from the quenching and cooling tank 42 for removal from the apparatus. The workpiece holders 14 then swing downwardly for transport by the chain 10 back to the loading Station 1.

From the foregoing, it will be aparent that workpieces, such as rocker arms, having oppositely extending portions to be hardened, such as the cup and pad ends of such rocker arms, and also having a region adjacent to the one end which is desired to be protected from hardness-inducing heating, such as the bore-containing portion adjacent to the cup end of certain rocker arms, can be so heat treated expeditiously and effectively to harden such ends without hardening to-be-protected-portion of the workpieces.

Various modifications may be made within the spirit of the invention.

We claim:

1. Apparatus operable to apply heat successively to a to-be-hardened portion of each of a plurality of similar workpieces for raising the temperature thereof to a hardness-requirement temperature while preventing an adjacent to-be-hardness-protected portion of each of such workpieces from experiencing a similar temperature rise, said apparatus comprising,

conveyor means for transporting the workpieces along a path of travel successively through a heating station in an attitude in which upper to-be-hardened portions lie above lower to-bc-hardness-protected portions and then through a quenching station,

a source of hardness-requirement-temperature-producible heat disposed above a source of cooling liquid at such heating station for simultaneous subjection thereto of the upper and lower workpiece portions, respectively, and

a source of quenching liquid at such quenching station for subjection thereto of at least the workpiece portions heated to hardness-requirement temperature at the heating station.

2. The apparatus of claim 1, in which said source of heat is in form of an inverted U-shaped induction heating coil, and in which said source of cooling liquid is contained in an open-top tank filled up to the level of said coil.

References Cited UNITED STATES PATENTS 1,178,027 4/1916 Scharwath 266-4 X 2,128,827 8/1938 Killian 13475 X 3,294,597 12/1966 Kuchera 2664 X 3,383,100 5/1968 Balzer et al. 3,385,583 5/1968 Jablonski 266-4 J. SPENCER OVERHOLSER, Primary Examiner R. S. ANNEAR, Assistant Examiner US. Cl. X.R. 134125, 126 

